We finally got some of the new Grey Knight plastics in recently, here are some pics of a set we did for Joan Company.
I wasn't too sure about the value of them going to plastic, until I saw the range of bits and the new codex - the kit can support a good range of builds. I hope GW plans on redoing all their plastic kits accordingly, so that people will be able to make any codex configuration with the bits available in any relevant kit.
Grey Knights are a good excuse for pulling out metal primes. Something useful to try is priming your minis in the same color that will be the dominant basecoat color - or at least as close as possible to it.
This allows you to do a much thinner, cleaner basecoat which means preserving more detail, and faster painting.
Brasses suggest the Adeptus Custodes, but copper or gold should work nicely with Grey Knights. Perhaps with washes of green and brown in to suggest the patina of age, and then highlighting in lighter golds (Burnished Gold?) or blends of golds and silvers. For no extra effort, that would make for a very distinctive looking Grey Knights army that would make everyone jealous. Yes, they wouldn't be grey, but then silver isn't grey either... A project I think I'll need to do myself some day.
Whether or not I'm keen enough on Grey Knights to get my own is one thing, but I'm definitely using their bitz. Their psybolt and psyflame gear is great for Ordo Malleus minis, and the teleporter packs demand to be used in any project you can get away with.
I'm a big fan of In the Emperor's Name, a new, elegant, rule set for 40k skirmish that rewards kitbashing, and the teleport packs work great for Imperial Guard special forces or kill teams.
If you're interested in Paintedfigs.com working on Grey Knights for you, you can always look us up at www.paintedfigs.com.